Job demands and dementia risk among male twin pairs

Abstract 

Background

Job characteristics may influence risk of dementia, but some types of job complexity remain to be examined. Twin studies provide a useful methodology for examining job differences between pairs who share many environmental and genetic influences.

Methods

Members of the National Academy of Sciences-National Research Council’s Twins Registry of World War II Veterans received a clinical evaluation for dementia and job ratings from the Dictionary of Occupational Titles.

Results

Co-twin control models (n = 220 pairs) indicated lower risk of dementia with greater job demands of reasoning, mathematics, language, and vocational training, with comparable results in case-control models (n = 425 cases). These effects were significant among twin pairs discordant for ≥6 years, but not among those discordant between 3–5 years. Results were similar for Alzheimer’s disease, and the main effects were not further explained by zygosity or apolipoprotein E genotype.

Conclusions

Jobs that utilize data, academic skills, and extensive vocational training may protect against dementia. However, in twin pairs, these effects only emerged among individuals who remained free of dementia several years after onset in their sibling.

Keywords: Dementia, Alzheimer’s disease, Twins, Occupation, Job complexity